Arrikrutz Oñatiko Kobak

Arrikrutz Oñatiko Kobak is a karst cave system in the municipality of Oñati, at the gateway to the Aizkorri Natural Park, in the province of Gipuzkoa in the Basque Country.

What is this place?

Arrikrutz is part of the wider Gesaltza-Arrikrutz-Jaturabe complex, a network of around 14–15 kilometres of interconnected galleries spread across six overlapping levels — the largest cave system in all of Gipuzkoa. The rock itself is limestone and dolomite carved out by water, dating back to the Upper Jurassic and Lower Cretaceous periods, somewhere between 96 and 154 million years old. The site sits close to the Sanctuary of Arantzazu, one of the most important pilgrimage destinations in the Basque Country.

What will you see inside?

The tourist route runs through what is known as Gallery 53, a 500-metre stretch with a 35-metre change in elevation, where visitors can admire rock formations shaped by water over thousands of years, along with large stalactites hanging from the gallery ceilings. The cave also preserves traces of ancient life: excavations have uncovered a complete cave lion skeleton, unique on the Iberian Peninsula, along with partial skeletons and skulls of panthers and a substantial deposit of bear remains. These archaeological and palaeontological finds make Arrikrutz one of the most significant sites of its kind in the region.

How do you get there?

The caves are located in the municipality of Oñati, in the heart of Gipuzkoa. Access is via a local road heading towards Aizkorri and the Sanctuary of Arantzazu — travelling by car is the most practical option, given the mountainous surroundings. Visits must be booked in advance by phone or online, as group sizes are limited.

How should you plan your visit?

The standard tour lasts about an hour and requires no special physical preparation, making it accessible to most visitors. Adults can also opt for a longer, more demanding speleology tour lasting roughly three and a half hours, which covers deeper sections of the system. The cave maintains a steady temperature of around 10°C year-round, so regardless of the season outside, warm clothing and sturdy, comfortable footwear are essential.

When should you visit?

The caves are open all year, and the constant internal temperature means the season makes little difference to comfort. It's a good option in summer as an escape from the heat, and in winter, when the inside of the cave is warmer than the air outside.

Frequently asked questions

How long does the visit to the Arrikrutz caves take? The standard tourist visit lasts around 60 minutes and covers Gallery 53. Those interested in the speleology option (available from age 18) can expect a tour lasting about three and a half hours.

Do you need to book in advance? Yes, visits must be reserved by phone or through the online booking form — group sizes are limited, and the cave can only be visited with a guide.

What should you bring along? Warm clothing, since the cave stays at a constant temperature of around 10°C, and comfortable, non-slip footwear, as the route crosses uneven, damp terrain.

What is the biggest highlight of this site? Beyond the rock formations and stalactites themselves, the palaeontological finds stand out — a complete cave lion skeleton, unique on the entire Iberian Peninsula, along with the remains of cave panthers and bears.